1. Field of the Invention
The invention relates to a battery pack that includes a plurality of battery modules.
2. Description of Related Art
In the related art, configuring a battery pack to obtain higher output voltage or the like, for example, by electrically connecting a plurality of battery modules together to form an assembled battery is known. Also, the battery modules that make up the assembled battery may each be formed by one single cell or by a plurality of single cells (that is, the battery modules that make up the assembled battery may each be formed as an assembled battery that is made up of a plurality of single cells).
Such battery packs having a wide variety of structures, from those with a small capacity that are used as power supplies for small electronic devices such as telephones and laptop computers, for example, to those with a large capacity that are used as power supplies for driving apparatuses of hybrid vehicles and electric vehicles and the like, for example, are in wide use.
It is known that it is important to efficiently release heat that is generated in these battery packs during use. In particular, when a secondary battery is used as a single cell that forms a battery pack, it is extremely important that heat be released efficiently when charging and discharging.
Therefore, in this technical field, proposals have been made to increase the heat dissipation efficiency of a secondary battery pack by, for example, providing ribs that extend in the direction in which cooling air flows on the surfaces of cases of the secondary batteries that make up a secondary battery pack so as to form a channel through which cooling air is able to flow between secondary batteries, as described in Japanese Patent Application Publication No. 2006-093144 (JP 2006-093144 A), or providing protrusions on surfaces of a partition wall that is arranged between single cells that make up a secondary battery pack so as to form a flow path through which cooling air is able to flow, between the single cells, as described in Japanese Patent Application Publication No. 2006-012847 (JP 2006-012847 A).
As described above, in this technical field, proposals have been made to increase the heat dissipation efficiency of a secondary battery pack by forming a space for flowing cooling air between single cells, by providing ribs that extend in the direction in which the cooling air flows on the surfaces of the cases of a plurality of single cells that make up a secondary battery pack, or providing protrusions on the surfaces of a partition wall arranged between single cells.
However, simply providing ribs that extend in the direction in which the cooling air flows on the surfaces of the cases of a plurality of single cells that make up a secondary battery pack results in the air only passing monotonically through cooling space, so a sufficient cooling effect is unable to be obtained. Also, when protrusions are provided on the surfaces of a partition wall arranged between single cells, the flow of air inside the cooling space becomes disturbed, which does improve the cooling effect to some degree. However, in large capacity battery packs used as power supplies for the driving apparatuses of hybrid vehicles and electric vehicles and the like, the amount of heat that is released during charging and discharging is large, so an even greater improvement in cooling efficiency is required.